Influence of geotechnical fills from recycled materials on groundwater
Industry produces large quantities of residues (waste materials and by-products), which are potentially suitable for beneficial use, for example as recycled materials in geotechnical applications as a substitute for natural raw materials. The prerequisite for the beneficial use of residues is their environmental acceptability and their technical adequacy. However, compared to natural raw materials, recycled materials can have a higher content of potential toxic contaminants, which can be inorganic or organic. This may present a limiting factor for the use of such materials, due to the potential release of the contaminants when the material comes into contact with water.
In the case of the production of geotechnical composites based on recycled materials, it is possible to produce chemical inert materials in which potentially toxic contaminants are effectively immobilized. Such composites can especially be used as geotechnical fill. However, one of the main concerns about the use of such new composites still refers to insufficient knowledge about their environmental properties, so that the leaching behaviour of such composites needs to be investigated thoroughly.
One of main objectives of the study is to investigate the storage and transport of contaminants which can be potentially released from three selected new composites (based on the use of recycled industrial and combustion residues, as well as of recycled sludge) that are produced and placed by TERMIT and HARSCO, and used as geotechnical fills. Investigated composites have different leaching potentials. Since the release of potentially toxic substances is difficult to monitor (the transport processes are still insufficiently explained), this research presents a challenge from both the scientific point of view, and the development perspective. Nowadays, there is also an increasing demand for development of sensitive, reliable, and cost and time effective monitoring tools for the detection of anthropogenic contaminants in subsoil and groundwater. This gap is aimed to be fulfilled within proposed project.
Three types of composites based on various recycled materials will be installed in the pilot testing laboratory (i.e. this will be located in the area owned by TERMIT). The materials which are relatively abundant, relatively difficult to recycle, and some of them involve components which are difficult to immobilize will be chosen. Part of the composites will be installed in the form of compacted layers and part in the form of non-compacted layers. In the latter case, less favourable conditions related to the higher permeability of the composite to infiltrating water (resulting in higher leaching potential) will be simulated. Leachates will be collected by means of lysimeters in order to study potential emissions of released contaminants. Passive samplers will also be used to determine the contaminants in the subsoil and groundwater.
The proposed project has following goals:
  • To determine the presence of potential contaminants in leachates released from selected composites.
  • To determine the impact of hydrogeological conditions on leachate emissions.
  • To improve the existing methods for performing monitoring of the contaminants which are released from geotechnical fills, and of their migration into the environment.
  • To prepare recommendations for the selection and use of the optimal combination of methods and for data analysis and interpretation.
  • To improve the existing method for the integration of leachate emissions which affect groundwater quality into LCA.
  • To find new business opportunities for circular economy and improve industrial symbiosis.
  • To develop self-assessment tools for stakeholders, in the sense that they will be able to evaluate sustainability of the procedures related with beneficial use of recycled materials.
  • To establish broad social acceptance in the field of beneficial use of recycrecycled materials in geotechnical applications
2018/07/01 - 2021/06/30
Slovenian Research Agency